The Iron Overload and Hereditary Hemochromatosis Study is an epidemiologic study of the prevalence, genetic and environmental determinants, and potential clinical, personal, and societal impact of iron overload and hereditary hemochromatosis in a multi-center, multi-ethnic, primary care-based sample of 100,000 adults. The information will be used to determine the feasibility and potential individual and public health benefits and risks of primary care-based screening and intervention for iron overload and hereditary hemochromatosis. The 100,000 participants will be recruited from five field centers for screening. Following the screening, a clinical examination will be conducted in selected individuals. The final component of the study is a family study which will use genome scanning and assessment of linkage to identify genetic variants related to the expression of iron overload and hereditary hemochromatosis disorders.